What is delirium?

Delirium happens when a person has sudden confusion or a sudden change in mental status. The person may have trouble paying attention or thinking clearly. They may act disoriented or distracted.

Delirium is more severe than having brief episodes of confusion or absentmindedness. It requires treatment and often hospitalization.

Is delirium a disease?

No, delirium is not a disease. It’s a changed mental state.

Is delirium the same as dementia?

Delirium and dementia (which includes conditions such as Alzheimer’s disease) have some similarities, but they are not the same.

  • Delirium mostly affects a person’s attention. Dementia affects memory.
  • Delirium is a temporary state that begins suddenly. Dementia is chronic (long-term) confusion that usually begins gradually and worsens over time.

However, someone can have both delirium and dementia. Seek care quickly if a person, especially one with dementia, begins to show symptoms of delirium.

What are the types of delirium?

The two types of delirium are:

  • Hyperactive delirium: The person becomes overactive (agitated or restless).
  • Hypoactive delirium: The person is underactive (sleepy and slow to respond).

Hypoactive delirium is more common, occurring in up to 75% of people with delirium. But many people, including healthcare providers, may incorrectly assume the person is depressed.

People can experience both types of delirium together. They can be extremely alert one minute and drowsy the next.

Who is at risk for developing delirium?

Delirium happens more often in older people and hospitalized patients. “Hospital delirium” can affect 10% to 30% of those patients.

People in these high-risk populations may develop delirium:

  • People who have had surgery.
  • 80% of people who are at the end of life.
  • 70% of people in intensive care units (ICUs).
  • 60% of people over age 75 in nursing homes.
  • 30% to 40% of people who have human immunodeficiency virus (HIV).
  • 25% of people with cancer.

People may also be at higher risk for developing delirium if they:

  • Are on dialysis.
  • Can’t move because of catheters or restraints.
  • Don’t get enough sleep or are dehydrated.
  • Have burns.
  • Have more than one illness, have a chronic condition or take multiple medications.
  • Have Parkinson’s disease, chronic liver disease or had a stroke.
  • Have trouble hearing or seeing.
  • Suddenly stop using alcohol or drugs (withdrawal).

How common is delirium?

Because delirium is temporary, it’s hard to know exactly how many people develop it. Researchers estimate that hospital delirium affects 15% to 50% of people.

Symptoms and Causes

What are the causes of delirium?

In some cases, providers can’t find a cause of delirium.

Known causes of delirium include:

  • Toxicity from overuse, overdose or withdrawal from alcohol and medical or nonmedical drugs.
  • Overwhelming reaction to infections such as pneumonia, sepsis and urinary tract infections.
  • Changes in the environment.
  • Dehydration.
  • Medications, such as those with anticholinergic effects (including antihistamines), psychoactive drugs and opioids.
  • Hormonal issues (such as hyperthyroidism or hypothyroidism).
  • Hospitalization or surgery.
  • Kidney or liver injury or failure.
  • Lack of oxygen to your tissues.
  • Lack of sleep.
  • Pain.

What are the symptoms of delirium?

The different types of delirium produce different symptoms. Symptoms tend to start suddenly and get worse over the next few hours or days. A person with delirium may act like they’re intoxicated. The main symptom is being unable to pay attention. Symptoms tend to become worse in the evening, which is known as sundowning.

Symptoms of hyperactive delirium include:

  • Acting disoriented.
  • Anxiety.
  • Hallucinations.
  • Rambling.
  • Rapid changes in emotion.
  • Restlessness.
  • Trouble concentrating.

Symptoms of hypoactive delirium include:

  • Apathy.
  • Decreased responsiveness.
  • Flat affect.
  • Laziness.
  • Withdrawal.

Diagnosis and Tests

How is delirium diagnosed?

Healthcare providers look for problems with attention, memory, orientation and visual ability. Providers may ask the person to perform a few simple tasks, such as spelling a short word backward or doing a basic math problem.

A provider may diagnose delirium if the person:

  • Can’t focus or shift attention.
  • Has changes in thinking.
  • Has a rapid onset of thinking problems, which may change throughout the day.

What tests are used to diagnose delirium?

After asking about the person’s symptoms, healthcare providers do a physical exam. They may also use other tests to help identify a cause, including:

Management and Treatment

How will the provider decide what treatment is best?

Other medical conditions usually cause delirium. It’s important to treat those conditions to treat the delirium. The provider will review the person’s:

  • Medical history.
  • Physical exam results.
  • Lab results.
  • Drug use, including over-the-counter drugs, illicit drugs and alcohol.

The person may not be able to answer questions about themselves. So providers may ask the person’s family member or loved one:

  • Did the confusion begin suddenly or gradually?
  • How quickly did it progress?
  • What was the person’s mental and physical state before this?
  • Is the person taking any drugs or dietary supplements?
  • Did the person stop or start any new medicines or drugs recently?

Does delirium require hospitalization?

In some cases, the person is in the hospital when they develop delirium. If they are not, they will most likely need hospitalization. In a hospital setting, providers can monitor them and keep them from injuring themselves or others.

Providers try to identify the cause of delirium quickly to get the patient treatment as fast as possible. Once providers identify and treat the reason, they can often reverse the delirium.

A team of multiple providers can help give the best care. It’s important to prevent related problems such as undernutrition and incontinence. A care team may include a:

  • Physician, nurse practitioner and/or physician’s assistant.
  • Physical therapist.
  • Occupational therapist.
  • Nurse.
  • Social worker.

How is delirium treated?

Treatment for delirium depends on the cause. Treatments may include:

  • Antibiotics for infections.
  • Fluids and electrolytes for dehydration.
  • Benzodiazepines for problems due to drug and alcohol withdrawal.

A healthcare provider may prescribe antipsychotic drugs, which treat agitation and hallucinations and improve sensory issues. Antipsychotic drugs include:

  • Haloperidol (Haldol®).
  • Risperidone (Risperdal®).
  • Olanzapine (Zyprexa®).
  • Quetiapine (Seroquel®).

How can I care for someone with delirium?

Often, treatments for delirium focus on the environment. It’s best if the person is in a quiet setting. If you are caring for someone with delirium, try these tips:

  • Promote good sleep habits: During the day, keep them awake, and expose them to sunlight. Avoid naps. Help them sleep at night by reducing noise and distraction.
  • Provide reassurance: Help them understand their environment. Explain what is happening.
  • Bring familiar objects: Surround them with items from home, such as photos, a blanket or a bedside clock. These things will help the person feel more comfortable in the environment. Try soothing music as well.
  • Encourage eating: Make sure the person eats and drinks nutritious food throughout the day, if appropriate.
  • Encourage movement: If it’s safe, help the person get out of bed and move around.
  • Help orient them: Talk about current events and family news to provide mental stimulation. Reading out loud can be helpful as well.

How can I help a person with delirium be independent?

The person should do as much as possible on their own. They may need some assistance in becoming independent. The person should:

  • Understand their care plan: Consider getting an interpreter if there are language barriers.
  • Be involved in their treatment: Encourage them to ask their provider any questions they may have.
  • Get support devices: They should use eyeglasses and hearing aids to promote good vision and hearing so they can communicate better.
  • Get out of bed: During the day, the person should be out of bed as much as possible. Help them sit in a chair during mealtimes or walk when possible.

How soon will a person with delirium start to feel better?

The symptoms typically improve in a few days to weeks. But someone who had delirium may have to stay longer in the hospital even after symptoms improve. They may still have an underlying medical condition or be unable to function completely on their own.


Can delirium be prevented?

Before you or a loved one has surgery, talk to your healthcare provider about assessing your mental status before the procedure. This way, your provider can establish a baseline. If your mental status changes after surgery, providers have presurgical measurements for comparison. And if you or your loved one has risk factors that increase your chances of developing delirium, talk to your provider.

These other tips can help prevent delirium:

  • Keep a clock and calendar nearby.
  • Have plenty of lighting during the day.
  • Talk to your healthcare provider about limiting medicines that aren’t needed, especially those that may cause delirium.
  • Drink plenty of water and other fluids.
  • Take a walk every day, or at least get out of bed and sit in a chair.
  • Talk to your healthcare provider if you have any signs of an infection, such as cough, fever, pain or shortness of breath.
  • Keep your family involved in the treatment plan.

What conditions put me at risk for delirium?

These conditions or situations raise the risk of developing delirium:

  • Cancer.
  • HIV.
  • Having surgery.
  • Being hospitalized, especially in the ICU.
  • Parkinson’s disease.
  • Dementia.
  • Chronic liver disease.

Outlook / Prognosis

What is the outlook for people with delirium?

Patients can recover completely if the cause of delirium is identified quickly and addressed. Any delay makes it less likely they’ll recover quickly and/or fully. Lack of treatment can lead to stupor, coma or even death. Older persons with dementia and those with HIV are less likely to have a complete recovery.

Is delirium fatal?

Delirium can be life-threatening if left untreated. But with the right care and treatment, people can recover.

How long does the person need to be on medication?

If a person receives medication to treat symptoms of delirium, the symptoms may improve. However, even when symptoms improve, the person should not suddenly stop taking their medications. A healthcare provider can help gradually decrease the dose and eventually stop the medication.

Living With

What are complications of delirium?

People with delirium may also have:

  • Longer hospital stays.
  • Medical complications, such as pneumonia and pressure ulcers.
  • Distressing memories of delirium, along with feelings of anxiety or fear.
  • Higher chance of needing full-time care.
  • Worsening mental abilities.

What side effects do delirium treatments have?

Antipsychotic drugs come with some side effects, although researchers are working on developing drugs that cause fewer side effects. Side effects are more common in older adults and can include:

  • High illness and death rates.
  • Stroke.
  • High-than-normal pulse rate with irregular heartbeats (sometimes occurs when haloperidol is delivered into a vein).

Benzodiazepines can cause:

  • Drowsiness.
  • Increased agitation.
  • Reduced control over behaviors.
  • Uncoordinated muscle movements.
  • Falls.

What should I ask my healthcare provider?

If a loved one is in the hospital with delirium, ask the provider:

  • What caused the delirium?
  • What treatment are they receiving?
  • Are they taking any medications for delirium?
  • Do the medications have any side effects?
  • How long will my loved one need to stay in the hospital?
  • What signs should I look for once they come home?
  • How can I continue to keep them safe?
  • What is the prognosis?
  • How can I prevent another episode of delirium?

A note from Cleveland Clinic

Delirium is a state of mental confusion that starts suddenly. It’s more common in older adults and people who are hospitalized. If you notice a sudden shift in mental status in a loved one — for example, they’re confused, disoriented and distracted — contact a healthcare provider. Prompt treatment can help most people recover fully from delirium.

Last reviewed by a Cleveland Clinic medical professional on 09/16/2020.


  • Delirium. ( Accessed 9/18/2020.
  • Merck Manual. Delirium. (,-spinal-cord,-and-nerve-disorders/delirium-and-dementia/delirium) Accessed 9/18/2020.
  • U.S. National Library of Medicine. Delirium. ( Accessed 9/18/2020.

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